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Error code reference

LG Hvac Error Code E654

Damper error

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Damper error — no switch input received for 100 seconds while monitoring the damper (time required for 5 turns of rotation).

First step from the service manual

Check if DAMPER motor connector (CN72) is dislocated from PCB; if so, reconnect it.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What E654 means on a LG hvac

The E654 error code on LG HVAC systems indicates a damper fault condition in which the system control board receives no feedback signal from the damper switch for a continuous period of 100 seconds. This 100-second window corresponds to the time required for the damper motor to complete five full rotations. When the PCB monitors damper movement and detects zero switch input pulses during this interval, it concludes that the damper mechanism has failed to operate correctly and triggers the E654 alert to prevent further system damage.

The damper itself is a motorized airflow control component responsible for regulating air distribution within the HVAC system. It communicates its position back to the PCB through a feedback switch that generates input signals as the motor rotates. A break in this communication, whether caused by a loose connector, a failed motor, a stuck damper blade, or a faulty switch, will cause the PCB to log this error. The motor connects to the control board through connector CN72, and a dislodged or improperly seated CN72 connector is the most frequent and straightforward cause of this fault.

Diagnosing E654 requires a systematic inspection starting at the CN72 connector on the PCB. If the connector is firmly seated and the wiring harness shows no visible damage, the next steps involve checking the damper motor for continuity and correct resistance, verifying that the damper blade is not physically obstructed or frozen in place, and testing the feedback switch for proper signal output during motor operation. A failed motor or defective switch will require component replacement to resolve the fault.

Source: manufacturer service documentation.

Common causes of E654

  1. 01

    Disconnected CN72 motor connector

    Wiring / connection

    The damper motor connector (CN72) may have come loose from the PCB, cutting off all communication between the motor and the control board. Visually inspect the connector and firmly reseat it if it is dislodged or partially pulled out.

  2. 02

    Damaged wiring harness

    Part replacement

    The wiring between the CN72 connector and the damper motor may be frayed, pinched, or broken, preventing feedback signals from reaching the PCB. Inspect the full length of the harness for visible damage or continuity breaks.

  3. 03

    Failed damper motor

    Part replacement

    The damper motor itself may have burned out or seized, leaving it unable to rotate and generate the required switch input pulses. Testing the motor for correct resistance and continuity will confirm whether it has failed.

  4. 04

    Defective damper feedback switch

    Part replacement

    The feedback switch that generates position signals during motor rotation may be faulty, causing the PCB to receive no input even if the motor is running. A switch that produces no signal output during motor operation will need to be replaced.

  5. 05

    Physically obstructed damper blade

    Wiring / connection

    Ice buildup, debris, or a mechanical obstruction can prevent the damper blade from rotating, stalling the motor before it can complete its rotation cycle. Inspect the damper assembly for blockages and clear any obstruction found.

See the test procedure for each cause

Frequently asked questions about E654

What does E654 mean on a LG hvac?
E654 means the LG HVAC system did not receive any switch input signal from the damper motor for 100 consecutive seconds, which represents the time needed for five full rotations. The control board monitors the damper to confirm it is moving correctly, and when no feedback is detected within that window, the system logs this fault. It can point to a loose connector, a wiring issue, a failed motor, or a blocked damper blade.
How do I fix the E654 error on my LG HVAC?
Start by checking whether the damper motor connector (CN72) is properly seated on the PCB, as a dislodged connector is the most common cause. If the connector is secure, inspect the wiring harness for damage and check that the damper blade can rotate freely without obstruction. If the wiring and blade are both in good condition, the motor or feedback switch may need to be tested for continuity and replaced if faulty.
Is the E654 error on an LG HVAC dangerous?
The E654 fault itself is not an immediate safety hazard, but it does mean the damper is not functioning correctly, which affects airflow control throughout the system. Running the unit in this condition can lead to uneven cooling or heating and potential strain on other components. It is best to address the fault before continuing normal operation.
How much does it cost to repair an E654 error on an LG HVAC?
If the issue is simply a disconnected CN72 connector, there may be no parts cost at all, and a technician visit for diagnosis and reconnection could range from roughly 75 to 150 dollars. If the damper motor or feedback switch needs replacement, parts and labor combined could range from approximately 150 to 450 dollars depending on the specific model and local labor rates. A proper diagnosis is needed before estimating total repair cost.
Will resetting my LG HVAC clear the E654 error code?
A power reset may temporarily clear the E654 code from the display, but the error will return if the underlying damper fault has not been corrected. If the damper motor connector is simply loose, reseating it before resetting the unit may resolve the issue permanently. For faults involving a failed motor, damaged wiring, or a bad switch, the code will reappear until the defective component is repaired or replaced.

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